1. Technical Field
The present invention relates to an improved data processing system. In particular, the present invention relates to cached object returned from a database query. Still more particular, the present invention relates to a context based cached infrastructure that enables a subset query over the cached object returned from a database query in a data processing system.
2. Description of Related Art
In the current enterprise JavaBeans™ (EJB) specification, lifecycle methods are provided for managing an entity bean's lifecycle. Examples of lifecycle methods include ejbCreate, which manages the creation of entity beans; ejbStore, which manages update of entity beans; and ejbRemove, which manages removal of entity beans. An entity bean is an enterprise JavaBean™ that has a physical data representation in a data store, for example, a row in a relational database table. Enterprise JavaBean™ or J2EE is a product available from Sun Microsystems, Inc.
In addition to lifecycle methods, enterprise JavaBeans™ specification provides ejbFind and ejbSelect methods to query entity beans that satisfy a search condition. For applications that seldom update their data, it is more efficient to cache the data locally rather than querying the database each time an update occurs, since database queries affect application performance.
Currently, query results may be cached and a user may search the query results by a certain criteria. For example, a catalog may have a “product” field and a “type” field, a user may search by the product, such as product=“electronics” or product=“books”. Since the catalog is seldom updated, the query results may be cached by the criteria, such that when the user performs the same search, the result is returned from the cached object instead of the database, thus, improving the search response time. If query results are cached without context, for each query, data may be returned if and only if it is an exact match.
Currently, no existing mechanism is present that allows a search to be performed on the subset of the existing cached query results. For example, to perform a search on query results returned by product=“books” for type=“bestsellers”. If all the “books” are already cached, it is more efficient to iterate the result of “books” and filter them to retrieve the “bestsellers”, rather than performing a separate search on the database based on the product and type.
In addition, no existing mechanism is available that sets up query results in such a way that makes it easy for user to iterate and filter query results. Therefore, it would be advantageous to have an improved method for a context based cache infrastructure that enables subset query over a cached object, such that database queries may be minimized to improve search performance.